The investment in the factory, which is being build outside Reno, Nev. and is expected to cost $5 billion, is an attempt by Panasonic to cement its future in automotive electronics, Panasonic President Kazuhiro Tsuga told reporters at CES this month.

Tesla

A Tesla Model S lithium-ion battery pack

In 2013, Panasonic extended a 2011 agreement to supply Tesla with automotive-grade lithium-ion battery cells. Panasonic increased its supply to nearly 2 billion cells over the course of four years.

Tesla also plans to use the Gigafactory to build batteries that store power generated from solar panels used on homes and businesses. Tesla's founder and CEO, Elon Musk, is chairman of the solar installer SolarCity.

SolarCity

Tesla's home battery, the white vertical box with the red label, is being piloted in 330 households, mainly in California.

Panasonic has been heavily involved in the development of photovoltaic cell technology -- the basis for solar power panels.

The new prototype solar panel has a solar energy conversion efficiency of 22.5% on a commercial-sized module. The prototype was built using solar cells based on mass-production technology, Panasonic said. The latest advance, in theory, allows Panasonic to squeak past SolarCity as having the most efficient solar panel in the world.